Optimal Design of Structures in the Framework of PBWE

A probabilistic procedure for the Performance-Based Design of buildings and other facilities subject to wind action is illustrated. The central objective of the procedure is the assessment of the dependability of the construction through the probabilistic description of a set of decision variables DVs. Each DV is a quantitative measure of a specific structural performance (occupant safety and comfort, structural reliability and integrity, building accessibility and functionality, etc.). The Aeolian risk with reference to any performance is conventionally measured by the probability of exceeding a relevant value of the corresponding DV; the probability is evaluated by taking into account the Aeolian hazard at the site, the calculated structural response and damage, and the correlation between the attained damage level and the relevant DV. The procedure is applied to an example case: the assessment of the occupant comfort requirement for a 74 storey building. Probabilistic calculations are carried out in frequency domain, but the parameters of the wind field are calibrated on the basis of the results of experimental tests, giving the time-histories of the total forces acting on a 1/500 rigid scale model of the building. The occupant comfort is related to motion perception and expressed by threshold values of the floor across-wind acceleration. Finally, the design of a Tuned Mass Damper is briefly illustrated, aimed at ensuring an adequate level of occupant comfort.